Antislap piston



May 23', 1933.

N. T. HARRINTON ANTISLAP PISTON 2 Sheets-Sheet l Filed Dec. '14, 1931 III ATTO RN EYS v M y 3, 1933- N. T. HARRINGTON ANTISLAP PISTON 2 Sheets-Sheet 2 Filed Dec ATTORNEYS Patent ed May 23, 933

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:mam T. mune'rom or emmm), ono

ANTISLAP ?MOR Application- 'e December 14, 1931 Serial no. 531.010.

The invention relates-to istons of that type adapted to be held against one wall of* the cylinder by resilient pressure suflicient to prevent or minimize' pisten slap and 4 5 forms in part a-oontinuation of my earlier filed application, Serial No. 533369. More specificelly, the invention has reference to pistons in which a sprin placed in a recess in the irt of the iston so as to bear a ainst one wall of the cy 'nder and to'press t e bod of the iston a ainst the opposite wall thereof. ne di culty encountered with this latter construction is the tendency for the shoe to move axially with respect to the recessed body due to frictional retarding of its movement along the cylinder wall. This will cause a reciprocation of the shoe in its recess during each reciprocation of the pisten which in time i. will wear the perts and produce a slap of a difl'erent character., Thus the main object of the Construction wili be defeated.

It is the object of the present invention to obtain a Construction in which slapping of the shoe in its recess is efiectuaily preven It is a further object to ohtain an improved Construction which is more efl'ective in preventing slap end et the same time is one which con be manufactured et low cost, With these objects in view the inventioh consists in the constriction as hereinefter set forth.

In the drewings: y Fi re i is o side eievation of the pisten showng'the some' within the cyiinder; higure 2 is on elevetion artly in sectionviewed at right engles to ie 1; Figure 3 is e horizontel section suhstehtiali of the exis of the wrist pim; to ere e pleh View end side eievetion respectivei oi the resillient expemder; Fires ti and Z ere views simiior to Fire 2 sowihg modified constructions; Figure 8 is e sectien simiier to Figure 3 showing whether modificetion; Fires 9 end 10 ere Views simiier to Fi ores i end 2 showing stiii another mod cetioh.

Piston slap is due primerily to rod engelerity which where the pisten ioosely fits i the cylinder will thrust it eiternetely against pressed shoe is .of the wrist pin axis. The 'present Construcingly shaped recess in the stonbody. In

in the pioneires t end 5 the opposite walls thereof in the plane of movement of the `red. It has been found thatthis sla ping movement can be best counter-acted hy resiliently holding the piston against one wall of the cylinder in a plane transverse to the plane of angular movement of the red, as this reduces the amount of pressure required. Thus various constructions have been designed for press- .ing the body of the piston` in the direction tion is of this eneral character and comprisesa shoe which surrounds the wrist pin and is in engagement with -a corresponddetail, A is the pisten hee B the skii-t, e the bosses or bearings projecting inwerd from the skirt for holding the wrst pin-D. surrounding the wrist pn and one of the bearings C therefor is an annular recess E for reoeiving a corres ondingly shaped shoe F., This recess meyeither concentric or eccentric with respect to the axs of the wrist pi-n and may also 'be of any desired contour such es round, ovel, square, etc. As shown in Figure 2 the recess E is circular in form end concentric with the axis of the wrist pin, the shoe F being of similar form. in Figure 6 the recess is of oval form end eccehtric to the amis of the pin and in Figure 7 it is substentially rectangtla'r in form. The shoe h ergeging the' recew E must heve -swumcient eieerehce therein for free movement, a this heing necessiteted by the thot thet cyiindere ot internet comhustion 85 when in operetion ere expended hy the heet ot comhustioh et their opper ends so es to impert thei-eto e, siight tapering .term. Conseqiehtiy in' eech reciprocation ot the engine the shoe must move inward te end outwerd in its recess to compensate tor the difiiereice iri diemete' ot the cyhnder ot its upper end tower ends. Where sutiicient cieerehce is provided to insure this freedom oi movement of the shoe in its re cess theme wiii eiso he freedom for .movement of the shoe in the direction of the enis of the pisten, this being occasioned hy drag on the shoe due to iriction with the oylinder wall which as before stated causes o a slap of the shoe alternately against the upper and lower walls of the recess.

To avoid the difliculty just referred to I have provided means for holding the shoe from movement in its 'recess axially of the pistonwhile permitting freedom of movement radially thereof. This may be accomplished in several wa s as follows: As shown in Figure 3 the soe F has arranged there-beneath within the recess E a corrugated ,resilient ring G which supplies the desired radial pressure. The points of contact between the corrugations of this rin and the shoe and also between the ringan the bottom of the recess are relatively limited in area. On the other hand, the external surface of the shoe which bears against the cylinder wall presents a contact area of much greater extent and consequently the contact pressure against these limited areas is much higher than the pressure against any equal area of the outer face of the shoe. I have discovered that this difference of 'pressure will produce an excess of friction between the shoe and the bottom of the recess over the friction between the shoe and the cylinder wall. While I am aware of the general law that friction is independent of the area of contact, nevertheless with these limited contact areas there appears to be a higher coeflicient of friction, doubtless due to the breaking through the lubricant film. Whatever the cause the practical efl'ect is that the shoe is held against objectional slap in its recess in an axial direction, even where clearance in said recess is considerable.

The fact that the shoe need not closely fit thewalls of the recess may be utilized in reducing cost of manufacture. Thus instead of requirin accurate machinin of the arts both the oe and the recess n the piston skirt may be formed by die casting. This* also permits of making these of different contours than would ibe possible if the surfaces required machining. Thus-as 'shown i in Figre 6 the shoe F is of an oval annular form and is arranged within a eorres ondmgly formed recess E'. In Figure the shoe F is of ta substantially rectangular 'form engaging a corresponding recess E'. In each -case the shape of the corrugated ring is of a similar contour.

he resistance to movement of theoorrugated ring G at the ints of contactigiay be partially due to t e imbedding of the.

sme in the contacting surface.- It is therefore desirable to provde' a suflicient number of corrugations so as to insure the radial arrangement of the same at ints in the crcle less than 180' degrees. referablyI jer-m eight corrugations, four projecting in one directiomand four in the &reverse direction. This will insure that at ,leasttwo of the corrugations on` each side will be ar- 'this strip J is corrugated at 'against the bottom of the recess so that the wear too deeply into the contacting surfaces This efl'ect may be avoided by the Construction-shown in Fi ure-8 in which H is a pressed steel cu tted within the recess E and having a ottom portion H' against which the corrugations of the ring G bear. The shoe F is provided swith another pressed steel cup I which is of a size to loosely fit within the cup H and which provides a bottom surface I' for contact with the corrugations of the resilient ring G.

Another modification of m invention is shown in Figure 9 in which t e shee is held b other means than friction against axial sli p; Thus as shown the shoe F i's attached to a steel strip J which is anchored at its end K to the piston skirt. A ortion of 4 to bear shoe is resiliently pressed outward against the cylinder wall. At the same time the a portion-of the strip J between the anchorin point K and the shoe form s a link whic positively holds the shoe from an movement relative to the skirt in the irection axially of the piston. With all of' these various 'modifications the same essential functions are performed viz, the free radial movement of the shoe in its recess and the prevention of any movement in a direction axially of the lpiston which would result in ob'ectionable s ap;

at I claim as my invention is:

1. The combination with a piston provided with a skirt portion having a recess therein, of a shoe n said recess having suflicient clearance therein for .free movement in a 2. The combnaton wth a piston provid-' ed with a skirt having a recess therein, of

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a shoe in said recess havin .suflicient clearanee th rein to permit of ree radial movement an a corrugated resilient member in said recess for' pressing said shoe in a radial direction and for also holding said shoe from 'slap in said recessin a direction axiall'y of the piston.

3.- The combination with. a piston provided with a skii-t having roundng the wrist pn, of a shoe in said a recess' therein surv of said shoe arranged within said recess and having bearings of limited area respeetively upon the bottom of said recess and upon said. shoe whereby the latter is pressed radially outward and is held from slap in said recess in a direction axially of the piston.

4. The combination with a piston provided with a skirt having a recess therein surrounding the -wrist pin,:of a shoe in said reeess having suflicient clearanee therei to permit a free radial movement and an annular corrugated resilient member eorresponding in shape to the outer `perphery of said shoe and a'rznged in said recess, the corrugations of said member forming bearings of restricted width on said shoe and on the 'bottom of the roeess extending in a radial slap in said reeess in a direction axially of the piston and a lining of harder metal adjacent to the member formed of softer metal for limiting wear by said corrugated meinber.

6. The combination with a piston provid-.

ed with a'skirt having a recess therein surrounding the wrist pin and a shoe in said rece ss having sufiicient olearance therein to permit of free radial movement, said piston skirt and shoe being formed of relatively soft metal, a corrugated resilient member in said recess for pressing said shoe in a radial direetionand for also holding said shoe from slap in said reeess in a directionaxially of the piston, and linings of harder metal for said shoe and the bottom of said recess to limit wear by the corrugations of said resilient member.. i

7. The combination with a piston provided with a skirt portion having a recess ther ein, of a shoe in said' recess having sufticient clearance therein for free movement in a 'adial direction, said piston and shoe being forned of relatively soft metal, a corrugated resilient member in said recess for pressing said shoe in a radial direction and for also holding said shoe from slap in said recess, and cups of harder metal arranged in said recess and upon said shoe for limiting the wear by the corrugations of said resilient metal. i

8. The combination with a piston provid-' ed with a wrist pin, of an annuhr shoe engaging the eylinder wall surrounding said wrist pin and resiliet means reacting on said shoe and piston to hold the latter against one wall of the cylinder.

` 9. The combination with a piston, a wrist pin and bosses projecting inwardly from the opposite sides of the piston orming bearings for said pin, of an unnular recess in one of said bosses surrounding the axis of the wrist pin, an annular shoe engaging said reeess and having its outer face fashioned to conform to the cylinder wall and resilient means within said recess reacting on said shoe and piston to holdthe latter against one side of the cylinderwall.

10. The conbination with a piston and a skirt thereof, of a wrist piu, bosses extending inward from opposite sides of the piston skirt forming bearings for said wrist pin, one of said bosses being enlarged in diameter and provided with an annular recess therein surrounding `the nxis of the wrist pin, an annular shoe eugaging said recess having its outer face conforming to the oylinder wall and resilient means Within said recess reaeting on said shoe and piston to hold the latter against one side of the cylinder wall.

I 11. The combinaton with a piston 'and wrist pin, of a boss projecting inwardly from the piston forming a hearing for said wrist pin and provided with an annular recess concentric with the axisiof the pin, an annular shoe engaging said reeess and ex-` ternally conforming, to the cylinder wall, and a warped resiliont ring within the recess in rear of said shoe for reaeting thereagainst and forciug said piston against one wall of the cylinder.

In testimony whereof I aflix my signature.

N ORMAN T. HARRINGTON. 

